1. Field of the Invention
The present invention relates to an ultrasonic wave motor used for driving a focus mechanism and a zoom mechanism of a lens barrel device, a printer, and a sheet feeding device, an ultrasonic wave motor-equipped device such as the lens barrel device, and a lens holding device.
2. Description of the Related Art
Conventionally, for example, an ultrasonic wave motor has been employed as a driving source of a lens of a camera by taking advantage of its characteristics such as silent operability, low-to-high driving speed capability, and high torque output. A driving device discussed in Japanese Patent Application Laid-Open No. 2011-227122 includes an ultrasonic wave motor configured of a lens holding member for holding a lens, a friction member positioned on the outer side in a radial direction of the lens which is capable of moving in an optical axis direction together with the lens holding member, and a vibration element for driving the friction member. This ultrasonic wave motor includes a roller disposed on a position facing the vibration element with the friction member therebetween, so as to make contact with the friction member. The roller functions as a guide mechanism for making the friction member rectilinearly move in the optical axis direction.
On the other hand, the lens holding member is configured integrally with the friction member so as to be held by two guide members provided on a lens barrel main unit. These guide members serve as a guide mechanism for making the lens holding member rectilinearly move in the optical axis direction. With the above-described configuration, the vibration element is held while being pressed by the friction member. When an ultrasonic wave vibration is excited in the vibration element in such a pressurized state, elliptic motion occurs in a contact portion of the vibration element corresponding to the friction member, so that the lens holding member configured integrally with the friction member makes a rectilinear movement.
However, the driving device discussed in Japanese Patent Application Laid-Open No. 2011-227122 includes rectilinear guide mechanisms for the friction member and the lens holding member, respectively, and thus the driving device is complexly configured of a large number of components at high cost. Further, because the lens holding member is integrally disposed on an ultrasonic wave motor unit that includes the friction member, the lens holding member is multiply fixed by a screw portion of the ultrasonic wave motor unit and the two guide members when the driving device is assembled into a finished state. Therefore, it is hard to say that the lens holding member can move smoothly.